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By R. H. Murray

The Kamyr countercurrent tower leach process consists of a true countercurrent leach ?with a flocculated ore and fibre mixture entering the top of the tower and a cyanide solution or alternative lixiviant as well as a barren wash solution entering the bottom of the tower. It offers the possibility of including the entire leaching, solid-liquid separation and clarification processes into one unit or tower as opposed to the multiple leach tanks, filtration and clarification sections required in a conventional leach and precipitation plant. The tower process has been demonstrated in the laboratory and found to be effective for leaching gold, silver and other amenable ores. Based on laboratory results, Gencor and Kamyr have jointly constructed a 200 ton per day pilot plant in order to prove the process on a larger semi-production plant scale.

Jan 1, 1989

By Martin N. Kelley

The Great Belt Link is a $3.5 billion fixed link across an 18 km (12 mile) wide body of water that separates the island of Zealand, on which Copenhagen is situated, and the main land mass of Denmark, Jutland, which is part of the European continent. The project consists of three main contracts. The first contract is an 8 km (5 mile) long, two-bore railway tunnel for the eastern half, the second contract is a 6.6 km (4 mile) combination railroad and highway bridge for the western half, and the third contract is a 6.7 km (4 mile) long high-level highway bridge for the eastern half. This paper will discuss the Eastern Railway Tunnel Project and the methods of construction that the joint venture consortium plans to use, along with its equipment selection. The ground conditions to be encountered begin with glacial tills, which are a mixture of clay, silt, sand, gravel, cobbles, and granitic boulders. The boulders can be up to 1-3 m (3-10 ft) in diameter. Underlying the till is a marl which is sometimes highly fractured with hydrostatic pressures of up to 8 bar. About 40% of the tunnel is in till and 40% in marl, with the remaining 20% being a mixed face of the two formations.

Jan 1, 1991

By R. L. Zick

The High Density Sludge Process was originally developed by Bethlehem Steel Corporation for use on acid mine drainage and diluted waste pickle liquor discharges requiring continuous chemical treatment systems. This work began in the early 1970s and was first put into practical use around 1973. To date there are approximately 15 operating systems which have been installed on mine drainage in the United States, and another 10 systems worldwide. Dense Sludge is an innovative and improved method for treating acidic metal bearing streams in a manner which minimizes the volumetric generation of sludge for disposal. The technology utilizes a sludge recycle process which forms particles that have a low affinity for water, unlike conventional metal hydroxide solids which contain tightly bound interstitial waters. Typical acid mine drainage streams contain high sulfate concentrations which combine with calcium ions in lime based treatment systems to form gypsum crystals. The physical form of this gypsum is radically altered when the Dense Sludge process is utilized compared to the form generated in conventional lime treatment systems. The characteristics of the metals particles are also changed in this process, as the metal hydroxides are converted to metal oxides. Slides No. 1 and No.2 show scanning electron micrographs of conventional and densified sludges illustrating these differences. The magnification used was 300X. The dense sludge particles settle faster, dewater more readily, are more easily pumped, and hold much less water than conventional precipitates. In some cases, because the metal content of the sludge is more concentrated, it can be economically recovered.

Jan 1, 1998

By R. L. Zick, D. C. Finn

Introduction The high-density sludge process was originally developed by Bethlehem Steel Corp. for use on acid mine drainage (AMD) and diluted waste pickle liquor discharges requiring continuous chemical-treatment. This work began in the early 1970s and was first put into practical use around 1973. To date, there are approximately 15 operating systems that have been installed to treat mine drainage in the United States. In addition, there are another 10 systems installed outside of the United States. The dense-sludge process is an innovative and improved method for treating acidic metal-bearing streams in a manner that minimizes the volumetric generation of sludge for disposal. The technology utilizes a sludge-recycle process that forms particles with a low affinity for water. These particles are unlike conventional metal hydroxide solids that contain tightly bound interstitial waters. Typical acid mine drainage streams contain high sulfate concentrations that combine with calcium ions in lime-based treatment systems to form gypsum crystals. Compared to the form generated in conventional lime treatment systems, the physical form of the gypsum is radically altered when the dense-sludge process is utilized. The characteristics of the metals particles are also changed in this process, as the metal hydroxides are converted to metal oxides. The dense-sludge particles settle faster, dewater more readily, are more easily pumped and hold much less water than conventional precipitates. In some cases, because the metal content of the sludge is more concentrated, it can be economically recovered. In general, the conventional and dense-sludge treatment processes are very similar. The changes required to implement the dense-sludge process are minor, and, typically, much of the existing equipment can be utilized. The net results of the process are: reduced operational costs associated with sludge generation, improved process control (particularly pH control), reduced gypsum deposition (i.e., less scaling) on system components and reduced sludge generation resulting in less return water for treatment. Despite the relative simplicity of the process, the application of the technology requires careful discrimination, and the "experience factor" for implementation is an important consideration that should not be over looked.

Jan 1, 2000

By N. Hoffman

Accurate, repeatable density measurements of a coal-magnetite-water slurry are difficult to achieve using a nuclear density gauge. Changes in the coal-to-magnetite solids ratio cause fluctuations in the readings of nuclear gauges. To investigate this problem the Electric Power Research Institute's Coal Cleaning Test Facility compared the performance of a nuclear density gauge on a coal-magnetite-water slurry with the performance of a differential pressure gauge modified with a new pressure sensor. A second aim of these preliminary tests was to determine if the differential pressure gauge is also sensitive to the type of solids in the slurry. This paper explains current slurry density measurement practices, describes the nuclear and differential pressure gauges used in the CCTF tests, and presents test methods and results.

Jan 1, 1986

By B. H. Kim

The use of a 25.4 mm diameter water-only hydrocyclone for separating fine-size (-150 µm), high-density (>4.5 g/cc) particles from similar-size, lower-density (2.65 glee) particles was investigated. It was found that a single-stage separation recovered nearly 90% of the heavy minerals (7.0 g/cc), while achieving a volume reduction of about 70%. The use of dense medium in a single stage improved volume reductions to 90% at similar heavy mineral recoveries. In addition, computer simulations of a three-stage circuit were performed, which showed that recoveries approaching 97% with volume reductions of 95% were possible.

Jan 1, 1998

By M. S. Klima, B. K. Kim

The use of a 25.4-mm- (1-in.-) diam water-only hydro-cyclone for separating liberated 125 x 25- µm high-density particles from similar-size lower-density (2.65 g/cc quartz particles, as might be used in soil washing applications, was investigated. As expected, cyclone performance was greatly affected by changes in cyclone geometry and operating conditions. A single-stage separation recovered 75% of the magnetite (4.8 g/cc) while rejecting nearly 60% of the quartz. With ferrosilicon (7.0 g/cc) as the heavy component, the recovery improved to 85%. The use of dense medium in a single stage increased both ferrosilicon recovery and quartz rejection to approximately 90% each. In addition, computer simulations of a three-stage circuit were performed. The simulations showed that recoveries approaching 97% with quartz rejections of 95% were possible.

Jan 1, 1999

By R. Steele

In addition to compliance with government emissions and reporting requirements, mining and mineral processing companies are increasing energy efficiency to reduce costs and become more competitive in the global marketplace. One of the major obstacles to identifying opportunities for increased energy efficiency is the lack of readily available data on energy use, and more importantly the energy use linked to production data, that identify energy reduction opportunities. As well as energy reduction, mining and mineral processing companies often struggle with the prediction of energy use, and are often penalized for under or over forecasting. Once again, it is the lack of timely information that makes this prediction difficult. This paper looks at expanding the use of a Manufacturing Execution Systems by integrating with Energy Solutions. This will provide automatic, timely information, at a granularity that makes it easier to identify energy reduction opportunities, reduce energy costs, and better predict energy use in a mining and mineral processing operation.

Jan 1, 2011

By A J. Jonaitis

The DENVER Tube Press is a simple, high pressure (1500 PSI (100 bar» filtration unit, developed for processing difficult-to-dewater materials and to produce a handleable filter cake and clear filtrate product. Lab and pilot testwork conducted in Australia on coal fines (55-70\ -35 micron (400 mesh)) have shown that total moisture contents of less than 20\ are consistently achieved in the final cake products from the Tube Press. Currently, these coal super fines are sent to waste due to uneconomical mechanical dewatering methods, which were only able to reduce total moisture levels in excess of 30%. Calculated, throughput rates for the 500 Series Tube Press exceeded 1700 kg/hr (3750 lbs/hr). Feed solids concentration requirements are between 45 and 50\ to achieve these results.

Jan 1, 1993

By S. K. Mishra, S. B. Kanungo

Because conventional (physical) methods of ore dressing are not suitable for reducing the phosphorus contents of high-phosphorous manganese ores from Andhra Pradesh (AP) and the adjoining area in southern Orissa, India, the adoption of chemical methods becomes imperative. An attempt was therefore made to reduce the phosphorus content of partially beneficiated manganese ores from AP by roasting with sodium carbonate and then leaching with hot water. However, due to the higher phosphorus contents of the manganese ores from Nishikhal mines in southern Orissa, and because of their apparent resistance to dephosphorization by roasting with Na2CO3 alone, a mixture of Na2CO3 and NaCl was found to be necessary to reduce the phosphorus content to below 0.15%. Free-energy calculations at 700°C and above indicated that Na2CO3 (or Na2O as the active component) is a more active reagent than NaCl. Various process parameters, such as the temperature and time of roasting, the amount of sodium carbonate and the temperature and time of leaching, were studied to arrive at the optimum conditions for dephosphorization.

Jan 1, 2000

By F. W. Mueller

It seems to be a matter of general understnading that title extraction or use of ground water may not be used as the basis of a depletion deduction under the United States Revenue Code And indeed, I have been unable to find any precedent upon which to base such a deduction. It is for this reason that the Shurbet case, which is the subject of my discussion and is now before the Court, may well become a precedent as authority for the allowance or disallowance of a depletion deduction for income purposes. It is well known that the law recognized that capital is consumed in the process of extracting minerals, oil and has, other natural deposits, and timber (underscoring supplied). This exhaustion, or depletion, is likened to the using up of raw materials in manufacturing. The law, therefore, provides a deduction for depletion which is intended as compensation for the exhaustion of assets consumed in the production of income through severance of minerals, oil and gas, other natural deposits, and timber.

Jan 1, 1962

In subterranean mining operations, access to communication networks deep underground is critical for transporting data, voice and video, and other supporting applications that are essential for efficient and safe operations. Whether accessing sophisticated ERP or maintenance management systems, engaging in fleet management, video surveillance, or access control, or protecting miners with wireless locator systems, these networks serve as a literal lifeline between workers deep within mines and surface operations. For this, mining networks require more than permanently installed network cabling, it also requires unique deployable systems designed for quick installation, extension and even relocation as the active mine site area moves, or equipment is moved in and out.

Mar 1, 2014

By John Durkin, Steven Wirch, Fred N. Kissell, Steven Ruggieri

The Bureau of Mines has developed two expert systems to give advice on coal mine dust control, one for continuous miner sections, and another for longwalls. Prototype versions have been evaluated by coal operators and MSHA. Both systems query the user as to the nature and extent of the dust control problem. Typical questions asked deal with matters such as cutting sequence, current dust standards and characteristics of current dust control techniques. Advice given by the system generally does not focus on a single issue, but may suggest a variety of approaches consistent with the ability of the operator to practically implement what is suggested. Both were written using expert system development software called Insight 2+. The advantages of Insight 2+ for the user are: low cost, IBM-PC compatibility, and the fact that little prior experience with computers is required. For the developer, Insight offers an easy to use production rule language and goal driven structure as well as a wide variety of capabilities.

Jan 1, 1987

By Thomas G. Johnston, Garston H. Blackwell

The development of a block model for a copper molybdenum ore deposit is described. The early use of the inverse distance power estimator, and later transition to geostatistics and kr iging, produced block models suitable for global reserve estimates. Because the global reserve was inadequate for routine mine planning, the production blast hole assays were incorporated into the block model, resulting in excellent local grade prediction. The on site use of small mini, and more powerful personal computers for estimating grades is described. The development of a computer aided, interactive graphic, mine planning system utilizing the grade block model is detailed.

Jan 1, 1987

By Frederick Bradley Henderson

This study was initiated to investigate the occurrence of cinnabar in the oxidation zones of some mercury sulfide deposits. Seven mines or mine districts were visited and samples were taken from both the oxidation and primary zones of these deposits in order to compare their mineralogies and assess Vie chemical changes that took place during oxidation. As a result of the study of these specimens, several limiting factors are suggested for the chemical environments and processes active in both the deposition and oxidation of mercury sulfide deposits. The Mt. Jackson mine, near Guerneville, California (location map, fig. 1), was studied in some detail and forms the basis of this paper. The mine has not heretofore been described in detail in the literature. The Mt. Jackson mine is considered typical of mercury sulfide deposits occurring at the faulted boundaries of serpentinite bodies and enclosing sediments. Such mines are common in the California and Oregon Coast Ranges? Specimens collected by the author from the New Idria and New Almaden districts, the Mt. Diablo, the Culver Bear, and the Buena Vista mines in California, and the Opalite district (Cordero and Bretz, mines) on the Oregon-Nevada border were studied for comparison with the Mt. Jackson samples. The mine description, maps and sketches were composed from field maps kindly provided by Francis Fredericks, consulting geologist to the Sonoma Quick-silver Mine Inc. during the author's visit in 1962. Additional information was obtained from the company maps and minor corrections and interpretations were added by the author.

Jan 1, 1965

By R. Bhaskar

An airborne dust cloud is an ensemble of particles of varied size, density, shape and states of aggregation. An understanding and quantifying of the dispersion and deposition of the dust generated in mines is essential to the development of measures for reducing worker exposure to dust. In coal mining, the major portion of the dust is generated during the cutting of coal using either a shearer or a continuous miner. The major phenomenon affecting ambient concentration is the deposition of dust. Particle deposition may take place due to the effect of gravitational, inertial, electrostatic, and thermal forces, and mechanisms such as Brownian and eddy diffusion, and inertial impaction. The three major mechanisms of deposition in turbulent flow in mines are diffusion (Brownian and eddy), sedimentation and inertial impaction. The mechanisms determining particle deposition are size dependent.

Jan 1, 1990

By R. V. Ramani, R. Bhaskar

An airborne dust cloud is an ensemble of particles of varied size, density, shape and states of aggregation. An understanding and quantifying of the dispersion and deposition of the dust generated in mines is essential to the development of measures for reducing worker exposure to dust. In coal mining, the major portion of the dust is generated during the cutting of coal using a shearer or a continuous miner. The major phenomenon affecting ambient concentration is the deposition of dust. Particle deposition may take place due to the effect of gravitational, inertial, electrostatic, and thermal forces, and mechanisms such as Brownian and eddy diffusion and inertial impaction. The three major mechanisms of deposition in turbulent flow in mines are diffusion (Brownian and eddy), sedimentation and inertial impaction. The mechanisms determining particle deposition are size dependent. From a review of the literature, there appears to be a knowledge gap in the understanding of the deposition phenomena in mine airways. In order to obtain a better understanding of the deposition of dust for various particle sizes, and to develop a set of data for evaluating predictive mathematical models for dust-flow in mines, a series of dust flow experiments was performed under controlled conditions in mine airways. It appears that the deposition data generally follow the theoretical behavior of dust based on the combined effect of diffusional and gravitational deposition. In this paper, the findings of the study on the deposition of dust in mine airways and its dependence on size, velocity and concentration are discussed. A set of deposition equations that could be used to determine the approximate deposition at various points in a mine airway are presented.

Jan 1, 1992

By Bernard E. Weichman

The oil shales in the Piceance Creek Basin of northwest Colorado occur in the Parachute Creek member of the Green River formation. The oil shales were deposited in a unique environment of deposition which caused the mineral nahcolite (NaHC03) to be precipitated within the oil shales. Post-depositional tectonics resulted in extensive fracturing of the Middle Zone of the Parachute Creek member, and to a lesser degree portions of the Lower Zone, which allowed percolating ground waters to dissolve the nahcolite in the fractured portion of the oil shale beds which is characterized by broken porous oil shale, certain beds of which have collapsed into rubble and debris. The extent and porosity of the Leach Zone aquifer is dependent upon the percentage of kerogen and nahcolite originally deposited in the oil shale. Any oil shale development program in the Piceance Creek Basin of northwest Colorado will need to be preceeded by an extensive study of the Leach Zone in order to determine the effects on a mining program.

Jan 1, 1973

By John C. Ferm

The role of geology in coal exploration, mine planning and mine development has, in the past, been relatively small. The primary reason for this lies in. the simplicity of geologic concepts that were necessary to bring these operations about. These concepts can be briefly stated as follows: 1) coal occurs in the beds or layers and is overlain and underlain by shales, sandstone or limestone in varying porportions, 2) each coal bed has been given a name and certain quality characteristics can often be associated with a named bed and 3) coal beds (and their adjoining rocks) are often folded into broad anticlines or synclines and, in some places, displaced or faulted. In actual practice, however, these simple principles have been found wanting. Thickening, thinning, pinch outs or changes in coal quality occurred but the occurrence was apparently unpredictable and the only real solution to such problems seemed to be practice and experience. This combined with ingeneous engineering solutions have provided answers to most questions. Perhaps a more fundamental reason that geology could offer so little input to coal mining is that the thickest, most persistant and best quality coal seams followed the above stated rules fairly well. In many areas, however, such seams are now nearing exhaustion and the increased demand for clean, non-polluting, safe energy is quickly bringing a need for techniques of exploration and mining procedures that will make development of formerly unminable seams a profitable venture. For the past 20 years some considerable body of knowledge has been added to the framework of the geology of sedimentary rocks and it is the purpose of this paper to present some of these newer ideas that will be useful in solving some of the present problems of coal exploration and development.

Jan 1, 1976

By V. Ciribeni, R. J. Ferretti, C. de Arrieta, E. E. Rossi

The relationship between collector concentration and the solution pH at which flotation occurs is discussed for different minerals. When flotation results are plotted as log of the concentration against pH, the values define areas of total, partial or no flotation. The experiments were performed in three different conditions: a) floating with the same solution used for conditioning; b) floating with water at the same pH as the conditioning solution; and c) floating with water at pH = 7. In each case, the results obtained are quite different. It is suggested that the presence of a second layer of collector reduces flotation over some domains in the graphs. These domains are called depression areas.

Jan 1, 1992